Abrasion and Wear of Rubber. Analysis of Wear Curves

1952 ◽  
Vol 25 (1) ◽  
pp. 107-109
Author(s):  
J. M. Buist
Keyword(s):  
Mathematical Method ◽  
Test Data ◽  
Wear Test ◽  
Broad Application ◽  
Rubber Industry ◽  
Wide Range ◽  
Subsequent Discussion ◽  
Abrasion Testing ◽  
Wear Index

Abstract One of the difficulties of assessing wear test data of rubber articles, e.g., tires, soles and heels, etc., is the fact that the wear index is not necessarily constant throughout the wearing trial. In a previous publication it was suggested that before exact correlations could be established between laboratory and service tests some mathematical method of obtaining constant indexes for both tests must be found. In the subsequent discussion of this paper at Birmingham, the author revealed that wear curves obtained on the Martindale abrasion tester and also some actual road wear curves could be expressed satisfactorily by an equation of the type y=axn. Since that time further work has been done, and it is now proved that if wear curves obtained on a wide range of laboratory machines, e.g., Martindale, du Pont, and Dunlop (Lambourn), are plotted, these curves are all of the same family y=axn. Although this equation is purely empirical, it is of considerable interest to the rubber industry in that it has such a broad application in the field of laboratory abrasion testing and also in service wear trials.

Analysis of Thick-Walled Pipeline Elements Operating in Creep Conditions

2015 ◽  
Vol 712 ◽  
pp. 63-68
Author(s):  
Przemysław Osocha ◽  
Bohdan Węglowski
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Creep Test ◽  
Power Plants ◽  
Steam Pressure ◽  
Creep Model ◽  
Creep Process ◽  
Fe Model ◽  
Element Analysis ◽  
Wide Range

In some coal-fired power plants, pipeline elements have worked for over 200 000 hours and increased number of failures is observed. The paper discuses thermal wear processes that take place in those elements and lead to rupture. Mathematical model based on creep test data, and describing creep processes for analyzed material, has been developed. Model has been verified for pipeline operating temperature, lower than tests temperature, basing on Larson-Miller relation. Prepared model has been used for thermal-strength calculations based on a finite element method. Processes taking place inside of element and leading to its failure has been described. Than, basing on prepared mathematical creep model and FE model introduced to Ansys program further researches are made. Analysis of dimensions and shape of pipe junction and its influence on operational element lifetime is presented. In the end multi variable dependence of temperature, steam pressure and element geometry is shown, allowing optimization of process parameters in function of required operational time or maximization of steam parameters. The article presents wide range of methods. The creep test data were recalculated for operational temperature using Larson-Miller parameter. The creep strain were modelled, used equations and their parameters are presented. Analysis of errors were conducted. Geometry of failing pipe junction was introduced to the Ansys program and the finite element analysis of creep process were conducted.

scholarly journals High variability in transmission of SARS-CoV-2 within households and implications for control

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259097
Author(s):  
Damon J. A. Toth ◽  
Alexander B. Beams ◽  
Lindsay T. Keegan ◽  
Yue Zhang ◽  
Tom Greene ◽  
...  
Keyword(s):  
Test Data ◽  
Attack Rate ◽  
Serological Test ◽  
Close Contact ◽  
Antibody Test ◽  
High Variability ◽  
Test Accuracy ◽  
Household Transmission ◽  
Wide Range ◽  
Test Specificity

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy. Methods We compiled serological SARS-CoV-2 antibody test data and prior SARS-CoV-2 test reporting from members of 9,224 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population. Results We estimated that individuals in our study households had a 0.41% (95% CI 0.32%– 0.51%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 36% (27%– 48%), substantially higher than the crude estimate of 16% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.41 (0.33–0.52) to avoid continued growth of the pandemic in Utah. Conclusions Our findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

scholarly journals Estimation of Transmissivity and Permeability in Swedish Bedrock

1977 ◽  
Vol 8 (2) ◽  
pp. 103-116 ◽  
Author(s):  
Leif Carlsson ◽  
Anders Carlstedt
Keyword(s):  
Statistical Analysis ◽  
Test Data ◽  
Hydraulic Properties ◽  
Pumping Test ◽  
Crystalline Rocks ◽  
Wide Range ◽  
Well Loss

Statistical analysis of pumping-test data from wells have been used to calculate average values of transmissivity and permeability in different Swedish rocks. The influence of the well-loss on the calculations is discussed. The highest values of transmissivity and permeability of the investigated rocks are found in the sandstones of Algonkian and Cambrian age. The Archean crystalline rocks show a wide range of results, and of the investigated rocks the gneisses seem to be more permeable than the granites. However, the degree of tectonization affects the hydraulic properties of the rocks considerably.

Comparative Study on the Wear Behavior of FPM and NBR in the Natural Crude Oil Medium

2013 ◽  
Vol 456 ◽  
pp. 349-353
Author(s):  
Zhe Wang ◽  
Shi Jie Wang
Keyword(s):  
Friction Coefficient ◽  
Crude Oil ◽  
Wear Behavior ◽  
Testing Machine ◽  
Wear Test ◽  
Premature Failure ◽  
Oil Drilling ◽  
Rotating Speed ◽  
Before And After ◽  
Abrasion Testing

The wear behavior of stator rubber in the natural medium of crude oil in oil-drilling screw pumps directly matters to its service life and sealing property. The premature failure of stator rubber is the main cause for the shortening life of screw pumps. In order to study the wear mechanism of NBR and FPM, a friction wear test was conducted at room temperature by using a MPV-600 micro-computer-controlling grain-abrasion testing machine, in which NBR, FPM and 45# steal pair are the testing subjects. SEM was afterwards employed to observe the surface topography before and after the rubber wear. The test result shows that at the constant low load, the wear extent of FPM increases in a stable, linear way when the rotor rotating speed increases, and the wear extent of NBR increases with the increasing speed of the rotor rotating speed. However, when the rotating speed is over 400r/min, the wear extent of NBR decreases instead. This might be attributed to the improvement of the local lubrication state on the friction surface. Much consistence is indicated in the changing rule of the friction coefficient of the two types of rubber and the changing wear extent with the rotating speed. At the constant, low rotating speed, the wear extent of NBR and FPM basically increases linearly, while the friction coefficient of NBR, FPM and steel pair decreases with the increasing load.

An Innovative System for Fretting Wear Testing Under Oscillating Normal Force

2000 ◽  
Vol 15 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
M. Z. Huq ◽  
C. Butaye ◽  
J-P. Celis
Keyword(s):  
Contact Resistance ◽  
Normal Force ◽  
Electrical Contact ◽  
Wear Test ◽  
Fretting Wear ◽  
Wear Testing ◽  
Mode Ii ◽  
Test Machine ◽  
Electrical Contact Resistance ◽  
Wide Range

Material damage caused by fretting wear is of significant concern in many engineering applications. This paper describes the design and performance of a new machine for the laboratory investigation of fretting wear under oscillating normal force (fretting mode II). The test machine uses an electromagnetic actuator to impose an oscillating normal force between the contacting bodies at a constant force amplitude over a wide range of frequencies. The principle of the actuation mechanism and the fretting wear induced with this particular wear test configuration are outlined in detail. Normal force and electrical contact resistance were measured on-line during fretting mode II wear tests. The performance of the wear test machine is illustrated by data obtained for different materials combinations, namely, hard materials, such as high-speed steel and (Ti,Al)N coatings oscillating against alumina ball counterbodies, and soft materials, such as a tin coating oscillating against the same. In general, wearing of the counterbodies was observed in the slip region. It has been observed that hard coatings and bulk ceramics are prone to fretting fatigue cracking. The evolution of electrical contact resistance in the case of the self-mated soft tin coatings tested under fretting mode II conditions is also reported.

scholarly journals Fabrication of photothermally active poly(vinyl alcohol) films with gold nanostars for antibacterial applications

2018 ◽  
Vol 9 ◽  
pp. 2040-2048 ◽  
Author(s):  
Mykola Borzenkov ◽  
Maria Moros ◽  
Claudia Tortiglione ◽  
Serena Bertoldi ◽  
Nicola Contessi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vinyl Alcohol ◽  
Near Infrared ◽  
Polymeric Materials ◽  
Photothermal Effect ◽  
Poly Vinyl Alcohol ◽  
Broad Application ◽  
Gold Nanostars ◽  
Wide Range ◽  
Spherical Gold Nanoparticles

The unique photothermal properties of non-spherical gold nanoparticles under near-infrared (NIR) irradiation find broad application in nanotechnology and nanomedicine. The combination of their plasmonic features with widely used biocompatible poly(vinyl alcohol) (PVA) films can lead to novel hybrid polymeric materials with tunable photothermal properties and a wide range of applications. In this study, thin PVA films containing highly photothermally efficient gold nanostars (GNSs) were fabricated and their properties were studied. The resulting films displayed good mechanical properties and a pronounced photothermal effect under NIR irradiation. The local photothermal effect triggered by NIR irradiation of the PVA-GNS films is highly efficient at killing bacteria, therefore providing an opportunity to develop new types of protective antibacterial films and coatings.

scholarly journals Food-Grade Pickering Emulsions: Preparation, Stabilization and Applications

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3202 ◽  
Author(s):  
Lijuan Chen ◽  
Fen Ao ◽  
Xuemei Ge ◽  
Wen Shen
Keyword(s):  
Solid Particles ◽  
Pickering Emulsions ◽  
Future Prospects ◽  
Stabilization Mechanism ◽  
Preparation Methods ◽  
Broad Application ◽  
Food Grade ◽  
Wide Range ◽  
Oil Water ◽  
Application Prospects

In recent years, Pickering emulsions have emerged as a new method and have attracted much attention in the fields of food sciences. Unlike conventional emulsions, Pickering emulsions are stabilized by solid particles, which can irreversibly adsorb on the oil-water interface to form a dense film to prevent the aggregation of droplets. The research and development of food-grade solid particles are increasingly favored by scientific researchers. Compared with conventional emulsions, Pickering emulsions have many advantages, such as fewer using amounts of emulsifiers, biocompatibility and higher safety, which may offer feasibility to have broad application prospects in a wide range of fields. In this article, we review the preparation methods, stabilization mechanism, degradation of Pickering emulsions. We also summarize its applications in food sciences in recent years and discuss its future prospects and challenges in this work.

scholarly journals Simple primitive recognition via hierarchical face clustering

2020 ◽  
Vol 6 (4) ◽  
pp. 431-443
Author(s):  
Xiaolong Yang ◽  
Xiaohong Jia
Keyword(s):  
Hierarchical Clustering ◽  
Test Data ◽  
Efficient Algorithm ◽  
Clustering Algorithm ◽  
State Of The Art ◽  
Experimental Results ◽  
Face Clustering ◽  
Wide Range ◽  
Hierarchical Clustering Algorithm ◽  
Bottom To Top

AbstractWe present a simple yet efficient algorithm for recognizing simple quadric primitives (plane, sphere, cylinder, cone) from triangular meshes. Our approach is an improved version of a previous hierarchical clustering algorithm, which performs pairwise clustering of triangle patches from bottom to top. The key contributions of our approach include a strategy for priority and fidelity consideration of the detected primitives, and a scheme for boundary smoothness between adjacent clusters. Experimental results demonstrate that the proposed method produces qualitatively and quantitatively better results than representative state-of-the-art methods on a wide range of test data.

Fatigue-Life Prediction Method Based on Small-Crack Theory in an Engine Material

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
James C. Newman ◽  
Balkrishna S. Annigeri
Keyword(s):  
Crack Closure ◽  
Test Data ◽  
High Cycle Fatigue ◽  
Fatigue Cracks ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Constant Amplitude ◽  
Notched Specimens ◽  
Wide Range ◽  
Stress Ratios

Plasticity effects and crack-closure modeling of small fatigue cracks were used on a Ti-6Al-4V alloy to calculate fatigue lives under various constant-amplitude loading conditions (negative to positive stress ratios, R) on notched and un-notched specimens. Fatigue test data came from a high-cycle-fatigue study by the U.S. Air Force and a metallic materials properties handbook. A crack-closure model with a cyclic-plastic-zone-corrected effective stress-intensity factor range and equivalent-initial-flaw-sizes (EIFS) were used to calculate fatigue lives using only crack-growth-rate data. For un-notched specimens, EIFS values were 25-μm; while for notched specimens, the EIFS values ranged from 6 to 12 μm for positive stress ratios and 25-μm for R = −1 loading. Calculated fatigue lives under a wide-range of constant-amplitude loading conditions agreed fairly well with the test data from low- to high-cycle fatigue conditions.

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